Write Journaling - CPU or HDD limited?

[mgrobins]

Hi,

Is Data Journaling tanking my write speeds likely to be due to CPU or HDD performance?

In attempting to isolate why my ReadyNAS Ultra 6 has poor write speeds (was getting 37MB/s using an SSD as a source over GB LAN) I disabled the "Full data Journaling" Option under the performance tab.

I am now getting ~80MB/s ... an increase of 100%.

The ultra 6 uses a 1.66GHz Dual Core atom processor and I am using Samsung F4 Spinpoint drives (4x 2TB) in an X-Raid2 arrangement.

Source file is on an SSD in my desktop connected by 1GB duplex connection.


My question: Is this speed change because of the CPU, HDD's or chipset?

I ask because I'd prefer to have journaling on and am about to get another NAS. If it's CPU related I'll be sure to get one with more grunt .

I do have a monitored UPS so it's not the end of the world turning it off but I like to be safe
Cheers,

 

[coxhaus]

I don’t know anything about the Ready NAS Ultra 6 devices but in general if you are journaling you are increasing the data being written. The best solution for journaling is a separate controller and hard drive away from the main controller and hard drives so as not to slow the main data flow.

 

[mgrobins]

Thanks. Good theory but not something I can do with this NAS .

Certainly food for thought for follow on purchase though.

I'm not sure what file system X-Raid 2 is based on. It's using full write (write-back?) journaling though.

What file systems have logical journaling? might be a better choice given the overhead on low power CPU models. Then to see what off the shelf NAS actually support them!

ReadyNAS OS6 uses a new one (Btrfx?) that isn't Ext based so I don't know much about it.

 

[stevech]

I've read other threads, here IIRC, about Netgear adopting that file system before it was proven/mature - leading to problems.
You can Google/search and find folks in the Linux world (not NASes) having issues with it.